Assignment # 1

--> DUE in class on Wednesday, January 11 at 10:30 am
You may handwrite your answers, but please write neatly and large enough so we can read it.

1.(a) By what percentage has the concentration of atmospheric CO2 increased globally since the year 1800?
(b) How do we know this?
(c) According to chapter 1 of the text and the lecture notes, what are the primary causes of this increase?

(a) about 30%
(b) Analysis of ancient atmospheric air bubbles found in ice cores taken from Greenland and Antarctic  ice sheets. The Keeling curve provides a direct modern records since 1958.
(c) The earliest part of the record has an increase from deforestation and early agricultural practices while the increase in the later part is from burning fossil fuels.

2. Do a google-search on "climate change" and follow 3-5 links from among the first ten. Spend a few minutes reading the materials on each link. Do the same thing for "global warming". Write a half-page essay (in complete well-constructed sentences) of your experience that compares and contrasts in general terms the material you found from for the two searches. Do the links generally confirm the definitions for these terms given in lecture and the textbook?

Some points I collected from you and from my own experience:
  • The web sites don't use the textbook distinction between global warming and climate change. Instead they tend to use them synonymously. Although there is a tendency for governmental sites to use climate change and environmental groups to use global warming
  • The web sites often don't give a definition, and sometimes assume their readers already know a great deal about the subject.
  • The EPA kids web site was one of the best for not failing on the previous two accounts.
  • Generally a search on climate change brought up governmental sites or scientific institutions, like the EPA, IPCC, and Pew Center. In contrast sites for global warming tended to be environmental groups.
  • Usually among the top five links for global warming would bring up at least one global warming skeptics sites.
  • Many of the sites appeared polarized about the issues, and didn't present material in a balanced way. Those with more scientific content seemed better. 
Some of you wrote about the actual scientific description of the problem. This was okay with me too, but I had in mind something more like a summary of the points I just made.

3. Explain what Daisyworld has to do with climate (use approximately 50 words).

See the textbook.

4. Planet BLIC is inhabited by creatures who have a strange attachment to black licorice ice cream and they attempt to coat their planet in it. The ice cream melts in the usual way.  Hence, ice cream coverage recedes when the temperature increases and advances when the temperature decreases. The black ice cream has a lower albedo than the natural surface, which is porous light-brown sand.  Assume that when ice cream melts, it disappears into the sand without a trace.

Part I. Using Fig 2-1 as a guide, fill in the missing arrowheads between boxes in the diagram for planet BLIC. Be sure to use normal and circular arrowheads to distinguish positive and negative couplings as in the book and lectures.  Also fill in the missing words on the lines. Note that (a) and (b) should each have just one arrowhead to show the coupling, and (c) should have two arrowheads to show the loop.  (sketch the figure on your paper if you wish)
BLIC diagram

Part II.  Draw a diagram like the one in Fig 2-10a in the text for planet BLIC but with the y-axis labeled "black licorice ice cream coverage". Use your imagination and explain the shape of the curves or lines that you draw. Label the curves or lines "black ice cream dependence on temperature" and "temperature dependence on black ice cream". Be sure to have exactly one intersection. Is the intersection point stable?

part I T=Temperature, C=Black ice cream coverage, P=stable equilibrium point at the intersection of the curves. (Negative feedback loops always have stable equilibria.)

C dependence on T is bowed slightly because we can imagine that the ice cream melt rate accelerates a little with increasing temperature. You could also imagine a straight line, if you wish, or maybe you would like to conduct a little ice cream melting research?

T dependence on C indicates temperature increases with ice cream coverage.

Note that the slopes of the curves matches the couplings indicated in Part 1.

Some of you tried to draw too close an analogy with Daisyworld and drew the C dependence on T as a parabolic curve. This implies a portion of the curve must have a negative coupling, which is not consistent with the information given in the problem. Biological systems often have parabolic dependence on temperature. Snow and ice melt